Equation of state and composition of the inner crust of an accreting neutron star: multicomponent model. (arXiv:2001.09739v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Shchechilin_N/0/1/0/all/0/1">Nikolay N. Shchechilin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chugunov_A/0/1/0/all/0/1">Andrey I. Chugunov</a>

Correct interpretation of X-ray observations of transiently accreting neutron
stars requires modeling of nuclear-physical processes in these objects. We
consider a chain of nuclear reactions that drives the crust composition in an
accreting neutron star and heats up the star. We constructed multicomponent
approach with the kinetics of nuclear reactions described in simplified
stepwise manner. The redistribution of nucleons between nuclei by emission and
capture of neutrons is shown to significantly affect the nuclear reaction
chains and the composition of the inner crust. In particular, even if the outer
crust has one-component composition, the appearance of free neutrons in the
inner crust leads to branching of reaction chains and formation of the
multicomponent composition. We apply the compressible liquid drop nuclear
model, which includes effects of free neutrons on nuclear energies. It allows
us to calculate the composition, the heating profile and the equation of state
of matter up to densities rho ~ 2 times 10^{13} g cm^{-3}.

Correct interpretation of X-ray observations of transiently accreting neutron
stars requires modeling of nuclear-physical processes in these objects. We
consider a chain of nuclear reactions that drives the crust composition in an
accreting neutron star and heats up the star. We constructed multicomponent
approach with the kinetics of nuclear reactions described in simplified
stepwise manner. The redistribution of nucleons between nuclei by emission and
capture of neutrons is shown to significantly affect the nuclear reaction
chains and the composition of the inner crust. In particular, even if the outer
crust has one-component composition, the appearance of free neutrons in the
inner crust leads to branching of reaction chains and formation of the
multicomponent composition. We apply the compressible liquid drop nuclear
model, which includes effects of free neutrons on nuclear energies. It allows
us to calculate the composition, the heating profile and the equation of state
of matter up to densities rho ~ 2 times 10^{13} g cm^{-3}.

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